The present invention relates to soldering in general, and more particularly to a method of soldering aluminum parts which are coated with solder, especially coolers and heat exchangers, and to an arrangement for performing such a method.
It is already known to heat aluminum parts which are coated with solder in continuous ovens in a plurality of stages performed in respective successive heating zones in which heated air and/or protective gas is moved over and/or through the objects to be soldered. The heating is continued until the solder melts, after which a cooling and cleaning of the soldered object is performed in a last zone. A forced aeration with heated air occurs in the heating zones, the temperature of the heated air being kept as close to the respective desired temperature for the respective heating zone as possible. The aluminum parts are moved either intermittently or continuously through the successive zones.
In this known continuous oven, it is not possible to maintain the temperature in the particularly critical soldering zone free from variations, inasmuch as colder air streams are able to penetrate into the soldering zone through the input and output openings for the objects and, in this manner, there occur temperature intrusions. For this reason, it is also not possible to provide an exact regulation of the temperature in the soldering oven to the melting termination temperature of the respective solder and a short dwell time of the object at this temperature, which is of the highest importance for a high-quality soldering; rather, there must be chosen an increased air temperature and/or an increased soldering time, and an increased air flow velocity must be provided, which under normal circumstances results in a deterioration of the soldering quality.